CVE-2023-36811 Archive spoofing vulnerability in borgbackup

Medium 4.7 Published Updated

Attackers with repository write access can spoof archives, potentially causing data loss during maintenance operations in borgbackup.

Exploited in the wild
Not known
Login needed
Any signed-in user
Attackable
Local or same network only
Victim action needed
Not needed
Fix
Available

What is CVE-2023-36811?

CVE-2023-36811 is a medium-severity vulnerability in borgbackup borg, published on 30 Aug 2023. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

borgbackup is an opensource, deduplicating archiver with compression and authenticated encryption. A flaw in the cryptographic authentication scheme in borgbackup allowed an attacker to fake archives and potentially indirectly cause backup data loss in the repository. The attack requires an attacker to be able to: 1. insert files (with no additional headers) into backups and 2. gain write access to the repository. This vulnerability does not disclose plaintext to the attacker, nor does it affect the authenticity of existing archives. Creating plausible fake archives may be feasible for empty or small archives, but is unlikely for large archives. The issue has been fixed in borgbackup 1.2.5. Users are advised to upgrade. Additionally to installing the fixed code, users must follow the upgrade procedure as documented in the change log. Data loss after being attacked can be avoided by reviewing the archives (timestamp and contents valid and as expected) after any "borg check --repair" and before "borg prune". There are no known workarounds for this vulnerability.

Weakness: CWE-347

Which versions are affected by CVE-2023-36811?

3 open source packages ship an affected version, including borgbackup. It affects 1 product.

PackageAffectedFixed in
borgbackup PyPIAll versions1.2.5
borgbackup PyPIAll versions1.2.5
borgbackup PyPIAll versions1.2.5

Products include Borgbackup Borg.

How do I fix CVE-2023-36811?

Upgrade borgbackup to 1.2.5 or later.

Is CVE-2023-36811 being exploited?

There is no known exploitation of CVE-2023-36811 in the wild and no public exploit code.

Sources

Also known as CLEANSTART-2024-EI10626, DEBIAN-CVE-2023-36811, GHSA-8fjr-hghr-4m99, PYSEC-2023-164, UBUNTU-CVE-2023-36811, openSUSE-SU-2024:13316-1.

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